1. Field of the Invention
The present invention relates to a method for removing offensive odors and infectious agents from recirculating building air, and an apparatus for carrying out the method, thereby increasing comfort within the building, reducing the need for make up air and reducing the energy required for the heating and cooling of the building.
2. Brief Description of the Prior Art
Many attempts have been made to remove offensive odors and infectious agents from buildings or rooms. The older methods include liquid and spray cleaning disinfecting agents. Liquid, solid, and spray odor masking agents have also been used for removing offensive odors and infectious agents from air. Other known methods includes activated carbon filters, and "one shot" oxidant impregnated or coated granules such as "Purafil", which consists of alpha alumina granules impregnated with potassium permanganate.
An example of a known method utilizing a cleaning and disinfecting agent may be found in U.S. Pat. No. 3,547,576 to Sheikh, which discloses an air sterilization process in which iodine crystals are volatilized and incorporated into air so as to kill bacterial organisms therein. Thereafter, washing the air mixtures with an iodine holding liquid captures the iodine in the air mixtures. A number of other known masking agents contain formaldehyde to deaden the sense of smell. However, in general, the scent of these commercial cleaning and odor masking agents is more offensive and irritating than the odor they eliminate or conceal. Further, the application of such commercial cleaner and odor masking agents also requires extensive labor in the frequent application thereof.
Activated carbon filters are effective in removing offensive odors, but the adsorbed organic material supplies an excellent substrate for the growth of infectious agents such as bacteria, fungi and viruses. Accordingly, the use such of filters, alone, has been found to be unsatisfactory.
Oxidant impregnated materials such as "Purafil" are effective in controlling odors. However, the oxidant becomes spent with use and accordingly, these granules are useable for a limited time period and must be replaced periodically (i.e., "one shot" use). The use of oxidizing agents for odor control on a continuous basis with recirculation of the oxidizing agent has been known, such as is described in U.S. Pat. No. 3,969,479, Lonnes et al. However, such methods also fail to provide for the regeneration of the spent oxidant and accordingly are also essentially "one shot" oxidizing methods.
It has also been known to utilize ozone for the purpose of purifing air (see U.S. Pat. No. 1,961,878 and U.S. Pat. No. 3,421,836). However, the introduction of ozone into the air in sufficient quantity to be effective as a disinfecting agent will also result in an unpleasant ozone odor which can be offensive to many people.
Accordingly, none of the prior art methods or apparatus for cleaning and disinfecting air can be used on a continuous basis without the need for frequent replenishment of the freshening agent, and without introducing unpleasant odor into the air being purified.